Gamma Jet 17 660' Reel Tennis String Reels : The Gamma Jet(TM) 17 660' Reel of tennis string offers players a unique string with technical features to enhance their game. This polyester monofilament string features a textured surface that provides players with excellent spin capability and better control. Ideal for players looking for max control, spin, and durability. Big hitters and tournament level players will do well with this string.